1. The Field of the Invention
This invention relates generally to measuring the refractive properties of the eye, and more particularly to a method and apparatus by which a patient may examine and measure the refractive properties of his/her own eyes in a more exact and objective manner than currently available.
2. The Background Art
Measuring the refractive properties of the eye is typically an iterative process, taking a fair amount of time, and involving more than one person, viz., a patient whose eyes are to be examined and an optical technician. The optical technician presents the patient with various calibrated lenses that have different optical properties and through which the patient views a displayed image or test pattern. With each lens, the optical technician asks the patient if vision with the current lens is better than with the immediately prior lens. The patient then attempts to remember and compare the prior image mentally stored in his/her brain with the current image, and make a subjective judgment as to which image is visually better. The comparison of current and prior images (viewed through current and prior calibrated lenses) continues until the patient decides that he/she has viewed the "best" image.
This decision, however, is made without any direct comparison of images. As a result, the patient oftentimes has difficulty being very conclusive about which image is better. This is evidenced by the fact that the patient frequently asks the technician to go back and forth several times between lenses before reluctantly making a decision. Of course, the optical technician has no way to "see" what the patient is actually seeing and has to rely on the patient's subjective memory skills and verbal communication.
Of current interest is a method and apparatus for objectively measuring the refractive properties of the eye, through direct observation of images, and without requiring an optical technician.